Amateurs spot a signal in the Kepler data that is later verified by scientists.

It's distinctly possible that the first truly Earth-like planet in another star system will be discovered by a non-scientist.

Well, that's not quite true: the process of discovery is more complicated than that. However, volunteers working with exoplanet data from NASA's Kepler telescope recently identified 42 planet candidates orbiting relatively nearby stars. Of those, 20 potentially lie within the habitable zone of their systems, meaning the basic conditions could be right for liquid surface water. One of these worlds, known as PH2 b, is definitely a Jupiter-sized planet clearly within its star's habitable zone. While the planet itself is unlikely to harbor conditions suitable for life, perhaps it has moons that would.

These volunteers were from Planet Hunters, part of the Zooniverse family of citizen science projects. Several Zooniverse efforts have yielded a number of scientific papers, proving that real science can arise from crowdsourcing. The latest Planet Hunter paper, which will be published in the highly ranked Astrophysical Journal, credited more than 40 citizen scientists, a collaboration that does credit both to them and to the professional scientists they worked with.

These projects excel in distributing tasks that cannot be automated with current technology, but which are sufficiently time-consuming that professional scientists (a category including graduate students) aren't able to devote enough attention to them. Based on the successes of the Zooniverse and related projects, it's clear that with a simple Web-based tutorial and a well-designed user interface, non-scientists can perform real research-related tasks.

Citizen science, thanks to the number of participants and cross-checking of results, is both efficient and incredibly successful. (In my teaching days, I had my Astronomy 101 students participate in the Galazy Zoo project for identifying galaxy types, and the Ice Hunters, a search for small objects in the outer Solar System.)

Mass transit, citizen-science style

The Kepler telescope locates planets by monitoring a patch of the sky 115 square degrees in extent. (For comparison, the full Moon is about 0.2 square degrees.) The telescope watches for slight variations in the light of stars that could indicate a transit: the small eclipse created when a planet passes in front of the star. The duration and depth (how much light is blocked) of the transit reveals information about the size of the planet and its orbit. This pattern is known as a light curve.

Transits are easiest to spot for large planets orbiting close to their host star. That's because those planets create the largest eclipses and undergo multiple transits in a short period of observation. By contrast, alien astronomers looking for Earth will only see it transit the Sun once every 365 days, and it will block only a tiny amount of the Sun's light when it does. Thus, it's a tricky task to discover planets orbiting sufficiently far from their host star to harbor liquid water.

The Planet Hunters project allows volunteers to look through various light curves, sorting out possible planet transits from other natural variations in starlight. These might arise from dim binary companions, brown dwarfs, or fluctuations in the star's output due to stellar weather. The premise of Planet Hunters is that human beings can sometimes be better at distinguishing between the different types of light curves than automated computer routines.

As with other citizen science projects, Planet Hunters makes sure multiple sets of eyes look at each candidate light curve. That ensures double- and triple-checking of results, helping to avoid false positives. Finally, professional exoplanet astronomers look at the light curves identified by the citizen scientists and make the ultimate decision. This process allows researchers to have a lot of confidence in the identifications—and the volunteers turn out to be very good at their work.

Looking for the sanctuary moon

The Planet Hunters identified 42 exoplanet candidates, including 33 with at least three transits—the more transits we can observe, the more reliable the identification as a planet, and the better the estimates of orbital characteristics. Forty of the potential exoplanets have orbits longer than 100 days, and 9 may have orbital periods greater than 400 days, placing them farther out than most previously identified worlds.

Based on their light curves, these candidates are mostly giant planets: Neptune-sized or larger. However, 15 out of the 42 could lie in their star's habitable zone, based on a simple model of planetary temperature. (Five more may also be in the habitable zone, but the observations are only based on two transits, too few to make precise orbital measurements.) If these resemble the giant worlds in our Solar System, then they may have very planet-like moons: an ocean moon like Europa, but with a surface uncovered by ice. That possibility is pleasing to Star Wars fans, as well as scientists.

Of the candidates, one stands out as a definite detection: PH2 b, determined to be a planet to 99.92 percent confidence thanks to follow-up observations using the Keck telescope. (The "PH" in the name is in honor of the Planet Hunters who discovered it.) PH2 b is about 10 times the diameter of Earth, placing it firmly in the giant planet category. It orbits its host star in approximately 282.5 Earth days. The researchers assumed a Jupiter- or Neptune-like atmosphere, and as a result determined it orbits within its system's habitable zone. If it has moons, they might possess liquid water.

Of course, habitability as we currently understand it is a function both of location and of history. After all, Venus lies within the Solar System's habitable zone, but harbors no liquid surface water; Mars, which lies outside the habitable zone, has evidence of past surface water, but is dry now. Nevertheless, with larger numbers of exoplanets in the database, we will have better statistics to assess the probability of liquid water in coming years.

Thanks to citizen science projects like Planet Hunters, you could play a significant part in the discovery of habitable worlds.

28 Reader Comments

Since each of the gas giants in out solar system have large moon systems, it makes me wonder if you could have multiple Earth-like moons orbiting the same planet, a sort of celestial Garden of Edan of habitable words.

It is worth contemplating that these planets only represent what is in our visible spectrum. There is an infinite amount of universe which exists beyond our sense perception.

There really isn't, in any meaningful sense of the term "exists." Kepler's camera is actually sensitive to a slightly different range of wavelengths than our eyes (400-865nm vs. 390-750nm for the visible spectrum). The real limitations of Kepler's planet-hunting are several factors that have little to do with the visible spectrum: 1) It is only surveying a very small patch of the sky.2) Many planets would have orbital periods that are far longer than Kepler's mission (Jupiter takes almost 12 Earth years to go around the sun, Kepler won't last that long). Kepler can only definitively pick out planets as they transit their stars. 3) It's limited to studying stars that are set at very narrow range of angles from the Kepler telescope; it has to see them almost perfectly edge-on to work. 4) Some planets may be too small to show up in Kepler's studies because they just don't have much impact compared to the stars they're orbiting.

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Reviewing "The Secret Commonwealth" by Rev. Robert Kirk illustrates a different realm we are still not attempting to pioneer.

You mean this Secret Commonwealth? Somehow I don't think elves will take kindly to NASA probes landing in Alfheimr.

I take serious issue with labelling these people as "non-scientists". They might not be professional scientists. They might not have science degrees. That doesn't make them non-scientists. If they're doing the work of science with the intent to increase knowledge then they're scientists.

(and before you ask, yes, I do have a degree in geology even if it is just a B.S.)

It is worth contemplating that these planets only represent what is in our visible spectrum. There is an infinite amount of universe which exists beyond our sense perception. Reviewing "The Secret Commonwealth" by Rev. Robert Kirk illustrates a different realm we are still not attempting to pioneer.

So how does one define "Citizen Scientist." Is this just a scientist without a lucrative government grant or what? Or maybe it is a scientist who doesn't have a board of education peddling his books so he can stay cooped up in a lab/observatory all day and night?

It is worth contemplating that these planets only represent what is in our visible spectrum. There is an infinite amount of universe which exists beyond our sense perception. Reviewing "The Secret Commonwealth" by Rev. Robert Kirk illustrates a different realm we are still not attempting to pioneer.

Please, Ars Technica, enough with the "artist's impression of what something the artist has absolutely no idea about might possibly look vaguely like". It's insulting to the reader's intelligence - the picture at the top of this article has absolutely no relationship with reality other than the artist's decision to label it as "this is what so and so might look like" and Ars Technica's decision to run with that.

Please, Ars Technica, enough with the "artist's impression of what something the artist has absolutely no idea about might possibly look vaguely like". It's insulting to the reader's intelligence - the picture at the top of this article has absolutely no relationship with reality other than the artist's decision to label it as "this is what so and so might look like" and Ars Technica's decision to run with that.

OTOH, they're quite popular with people. If we're going to continue to do "unproductive" science like this, we have to capture the imagination of the general population, and that means pretty pictures.

Don't tell me you choose your games exclusively based on their gameplay, and the eye-candy means nothing to you. Even if you do, the overwhelming majority of people prefer eye-candy to stimulating gameplay. This is the same thing.

Please, Ars Technica, enough with the "artist's impression of what something the artist has absolutely no idea about might possibly look vaguely like". It's insulting to the reader's intelligence - the picture at the top of this article has absolutely no relationship with reality other than the artist's decision to label it as "this is what so and so might look like" and Ars Technica's decision to run with that.

OTOH, they're quite popular with people. If we're going to continue to do "unproductive" science like this, we have to capture the imagination of the general population, and that means pretty pictures.

Don't tell me you choose your games exclusively based on their gameplay, and the eye-candy means nothing to you. Even if you do, the overwhelming majority of people prefer eye-candy to stimulating gameplay. This is the same thing.

Game publishers got in trouble several years ago because pictures on the box bore no relationship to what the game actually looked like. Would you like to try another analogy?

Please, Ars Technica, enough with the "artist's impression of what something the artist has absolutely no idea about might possibly look vaguely like". It's insulting to the reader's intelligence - the picture at the top of this article has absolutely no relationship with reality other than the artist's decision to label it as "this is what so and so might look like" and Ars Technica's decision to run with that.

OTOH, they're quite popular with people. If we're going to continue to do "unproductive" science like this, we have to capture the imagination of the general population, and that means pretty pictures.

Don't tell me you choose your games exclusively based on their gameplay, and the eye-candy means nothing to you. Even if you do, the overwhelming majority of people prefer eye-candy to stimulating gameplay. This is the same thing.

Game publishers got in trouble several years ago because pictures on the box bore no relationship to what the game actually looked like. Would you like to try another analogy?

Who's selling you a planet? Because if you're in the market, I have this fool-proof plan that will get you some property on the moon. Just sign here...

So how does one define "Citizen Scientist." Is this just a scientist without a lucrative government grant or what? Or maybe it is a scientist who doesn't have a board of education peddling his books so he can stay cooped up in a lab/observatory all day and night?

Have you ever actually done science or are you just bitter for not getting allowed in to a university on the grounds of being incompetent?

If you think that scientists live from lucrative grants and have it easy you must be smoking some bad shit. Might want to change the supplier before it goes beyond hallucinations.

PS: Might want to get your fat ass away from the computer since it's the result of those evil scientists staying cooped up in the lab and developing the technology that is making your life a bit easier than it would be without all that technology. So show some appreciation instead of being an ass.

Please, Ars Technica, enough with the "artist's impression of what something the artist has absolutely no idea about might possibly look vaguely like". It's insulting to the reader's intelligence - the picture at the top of this article has absolutely no relationship with reality other than the artist's decision to label it as "this is what so and so might look like" and Ars Technica's decision to run with that.

Oh please, there's no insult to your intelligence in a clearly-labeled artist's impression. You're just attempting to elevate your personal preference to a universal "insult" because "cater to my personal preferences" is obviously a non-starter.

Please, Ars Technica, enough with the "artist's impression of what something the artist has absolutely no idea about might possibly look vaguely like". It's insulting to the reader's intelligence - the picture at the top of this article has absolutely no relationship with reality other than the artist's decision to label it as "this is what so and so might look like" and Ars Technica's decision to run with that.

So, what would be a better image to include? I think that such depictions, even if they turn out to be wrong, are a better starting point than to offer nothing at all. Or, consider how similar art has increased people's interest in dinosaurs which otherwise would be nothing but a lot of bones.

box211 wrote:

It is worth contemplating that these planets only represent what is in our visible spectrum. There is an infinite amount of universe which exists beyond our sense perception. Reviewing "The Secret Commonwealth" by Rev. Robert Kirk illustrates a different realm we are still not attempting to pioneer.

I'd rather not live on a planet consisting of dark matter for the same reason I'd rather not fly or ride in completely transparent planes or cars.

Quote:

The Planet Hunters project allows volunteers to look through various light curves... [t]he premise of Planet Hunters is that human beings can sometimes be better at distinguishing between the different types of light curves than automated computer routines.

As with other citizen science projects, Planet Hunters makes sure multiple sets of eyes look at each candidate light curve. That ensures double- and triple-checking of results, helping to avoid false positives.

So how long before we can start integrating this into a new generation of recaptcha?

So how does one define "Citizen Scientist." Is this just a scientist without a lucrative government grant or what? Or maybe it is a scientist who doesn't have a board of education peddling his books so he can stay cooped up in a lab/observatory all day and night?

Have you ever actually done science or are you just bitter for not getting allowed in to a university on the grounds of being incompetent?

If you think that scientists live from lucrative grants and have it easy you must be smoking some bad shit. Might want to change the supplier before it goes beyond hallucinations.

PS: Might want to get your fat ass away from the computer since it's the result of those evil scientists staying cooped up in the lab and developing the technology that is making your life a bit easier than it would be without all that technology. So show some appreciation instead of being an ass.

So how does one define "Citizen Scientist." Is this just a scientist without a lucrative government grant or what? Or maybe it is a scientist who doesn't have a board of education peddling his books so he can stay cooped up in a lab/observatory all day and night?

I believe "citizen scientist" is someone like me: interested in science, does experiements, even generates proper reports...but has no formal education, so can't publish or be considered a "proper" scientist by anyone.

So how does one define "Citizen Scientist." Is this just a scientist without a lucrative government grant or what? Or maybe it is a scientist who doesn't have a board of education peddling his books so he can stay cooped up in a lab/observatory all day and night?

I believe "citizen scientist" is someone like me: interested in science, does experiements, even generates proper reports...but has no formal education, so can't publish or be considered a "proper" scientist by anyone.

There are a number of distinguished Citizen Scientists -- starting with Benjamin Franklin and Thomas Jefferson. Leonardo da Vinci would qualify as a Citizen Scientist. Karl Jansky a Bell microwave engineer, who discovers cosmic radio waves would qualify as a Citizen Scientist.

Just because you don't have a diploma with PhD on it doesn't keep you from doing science.